Messages in this thread | | | From | Sadasivan Shaiju <> | Date | Mon, 24 Nov 2014 14:31:26 -0800 | Subject | Network throughput is reducedof in total bandwidth in Mips. |
| |
HI,
When using iperf with small buffers there is a performance degradation for 3.10 kernel from 2.6.32 kernel . Using profiling tools I am getting the following data.
2.6.32 kerne data ........ samples % symbol name 160321 39.1122 r4k_wait 43731 10.6687 __do_softirq 27547 6.7204 cvm_oct_napi_poll_68 16569 4.0422 _raw_spin_unlock_irqrestore 12537 3.0586 cvm_oct_xmit 7362 1.7960 kfree 5916 1.4433 tcp_ack 5480 1.3369 net_rx_action 5353 1.3059 __copy_user_common 5097 1.2435 put_page 4447 1.0849 __kmalloc 4361 1.0639 kmem_cache_alloc 4359 1.0634 skb_segment 4309 1.0512 tcp_v4_rcv 4120 1.0051 __inet_lookup_established 4016 0.9798 ip_route_input 4010 0.9783 napi_complete 3766 0.9188 tcp_write_xmit 3297 0.8043 free_hot_cold_page 3189 0.7780 kmem_cache_free
3.10 kernel data ....... samples % symbol name 186 8.6431 __do_softirq 127 5.9015 cvm_oct_napi_poll_68 80 3.7175 tcp_sendmsg 76 3.5316 tcp_write_xmit 72 3.3457 cvm_oct_xmit_lockless 71 3.2993 _raw_spin_lock_bh 48 2.2305 tcp_release_cb 47 2.1840 release_sock 44 2.0446 add_preempt_count 44 2.0446 tcp_transmit_skb 34 1.5799 skb_split 31 1.4405 sub_preempt_count 27 1.2546 dev_hard_start_xmit 25 1.1617 __srcu_read_lock 25 1.1617 skb_release_data 24 1.1152 tcp_ack 23 1.0688 __bzero 23 1.0688 _raw_spin_unlock_irqrestore 23 1.0688 ip_finish_output 22 1.0223 __copy_skb_header 21 0.9758 __kfree_skb 21 0.9758 ip_queue_xmit
Looks like mainly the delay is causing by tcp_sendmsg() and tcp_write_xmit() from the stack . However if the buffer is increased to default (128k) there is no performance Degradation . This is happening only for small buffers.
When iperf is used as below the bandwidth on 3.10 kernel is only around 600Mbps compared to 900Mbps in 2.6.32 kernel.
./iperf3 -c 10.162.103.131 -l 1500
When iperf is ran with default buffers as follows the bandwidth is same in 3.10 kernel and 2.6.32 kernel.
./iperf3 -c 10.162.103.131
Please let me know if there is any fixes available for this .
| |